Thermoplastic pavement marking materials have become the most widely used durable pavement markings on asphalt pavements such as asphalt roads. Preformed thermoplastic marking materials are much superior to painted marking materials since their service life is as long as the asphalt surface. These marking materials conventionally are colored thermoplastic materials, usually about 0.025 to 0.125 inches thick, normally white or yellow in color, and are used to define traffic control information, such as pedestrian walkways, the stop line for automobiles and signals for right and left turn lanes.
Such preformed marking materials are installed by two basic processes. In the case of an existing roadway or, in some cases, even in connection with a roadway that is being installed, the preformed pavement marking material is applied to the asphalt surface by means of an adhesive.
There are many problems presented by this method. The preformed pavement marking material cannot be installed when the ambient temperature is below 60.degree. F. or if the pavement temperature is below 60.degree. F. Such marking material cannot be installed within 24 hours of a rainfall or if the pavement surface shows any indication of moisture. When the ambient temperature drops below 40.degree. F. during the night after the material is installed, condensation will occur under the material which will loosen the adhesive bond of the preformed material to the pavement.
In high traffic areas there will be a concentration of oil or road film which will make the surface preparation very difficult and time consuming.
In addition, when existing pavement markings are to be removed, an extremely dusty and dirty condition is created in the area to receive the new overlay markings. All loose materials, adhesive, etc. must be removed before the new markings are installed.
In the case of new asphalt surfacing, the accepted practice is to apply the preformed pavement marking material as a part of the final surface preparation of the asphalt roadway. The advantage of inlaying the material in this fashio results in a much greater useful life of the material.
The basic problem in installing preformed pavement marking materials during the road construction is the coordination between the work crews that are installing the roadway and the work crews that are attempting to install the markings. It is extremely difficult to coordinate this activity and there is a very limited period of time as the asphalt cools down when the markings can be installed and this usually is about the same time that the finish pass of the asphalt roller is being made so that it is a very difficult task to accomplish.